Comments

403 forbidden is not an osTicket error code, its a HTTP status code which means that you do not have permission to access the page or resource. You would need to consult your webserver software's error log to see what file, and any other details pertaining to this error. This is not really something that we can assist you with much beyond telling you its permissions related.

As a side note I'm not sure what /api/ost-api.php is... because that is not an osTicket file.